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  • Description
  • Specifications


External high-power Site Radio Link

Topcon’s SRL-35 high-power wireless UHF radio modem provides the signal strength you’ll need to cover the largest Construction and Surveying sites. At *35 watts, the SRL-35 provides reliable signal strength up to 50 miles (80 km). Featuring a wide 70 MHz operating bandwidth coupled with user selectable channel spacing and a unique continuous data package correction algorithm, you’re assured of reliable operation across the site.

Compatible with most all third-party radios, the SRL-35 provides free of charge or fixed-priced wireless access to your data 24/7 (depending on frequency), as often as you need it. Use the SRL to create every solution from point-to-point to a large network with multiple modems – easily and at minimal cost.

Built to IP67 standards for the harsh conditions of the jobsite, Topcon’s SRL-35 features a weather-protected LCD display, integrated operator keyboard and reinforced connectors. There’s even an over-temp auto-shutdown temperature feature to protect your investment.

*25W limited output power version is available as an order option for geographical areas where regulatory restriction on output power applies.



  • High output power of up to 35Watt*
  • Wide 70 MHz (403-473 MHz) operating range
  • User selectable channel spacing (12.5, 20 or 25 kHz)
  • Fully compatible with 3rd party radio broadcast such as Satel, Trimble and Pacific Crest
  • Multi-function user interface to indicate current operating status and configure the radio modem
  • Automatic prevention of overheating
  • Industry standard IP67 rating to withstand harsh surveying and construction environment




Frequency Range 403 - 473 MHz
Tuning Range 70 MHz
Channel Spacing 12.5 / 20 / 25 kHz (SW selectable)
Frequency Error Tolerance < 1kHz
Type of Emission F1D
Communication Mode Half-Duplex
Carrier Power 10, 20, 25, or 35W / 50 ohm (default)
5, 10, 20 or 25W / 50 ohm (option*)
Carrier Power Stability +2 dB / -3 dB
TX Duty Cycle ** 100% (22°C / 35°C) 40%
35W 20 min / 13 min No limit
10W No limit / 50 min No limit
Sensitivity < -114 dBm (BER < 10 E-3)***
Co-channel Rejection > -12 dB
Adjacent Channel Selectivity >47 dB @12.5 kHz / > 52 dB @ 25 kHz
Intermodulation Attenuation > 60 dB
Spurious Radiation < 2 nW
Data Modem
Interface RS-232
Interface Connector IP 67, 8-pin ODU
Data Speed of RS Interface 300 - 38400 bps
Data Speed of Radio Interface 19200 bps (25 kHz)
9600 bps (12.5 / 20 kHz)
Data Format Asynchronous RS-232
Power and Electrical
Power Consumption (average) 1.8 W typical (Receive)
120 W typical (Transmit 35W output power)
100 W typical (Transmit 25W output power)
0.4 W typical (Sleep State)
Operating Voltage +9 to +16 Vdc
4-pin ODU MINI-Snap Size 1 (feeding)
Dimensions 189 (H) x 138 (W) x 71 (D) mm (with connectors)
Weight 1.42 kg
Antenna Connector TNC, 50 ohm, female
Enclosure Aluminium
Temperature Range Operating: -25°C to +55°C, -40°C to +75°C (absolute min / max)
Storage: -40°C to +85°C
Waterproof IP 67 (NEMA 6)

* Limited output power is available as on order option

** If high output power is used continuously or with a high duty cycle, the equipment generates excess heat. The output power is automatically decreased when necessary to prevent overheating. Typical operating times are shown in teh chart with diefferent ouptu powers and duty cycles @ 22°C and 35°C.

*** Depends on receiver settings.

**** ≥ +12 Vdc @ 35 W output power

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